The casting quality of ship inspection mainly includes appearance quality, internal quality and service quality. Appearance quality refers to the surface roughness, surface defects, size deviation, shape deviation and weight deviation of castings; The internal quality mainly refers to the chemical composition, physical properties, mechanical properties, metallographic structure of the casting and the holes, cracks, inclusions and segregation existing in the casting; Service quality refers to the working durability of castings under different conditions, including wear resistance, corrosion resistance, resistance to cold and heat shock, fatigue, shock absorption and other properties, as well as machinability, weldability and other process properties.

Casting quality has a great influence on the performance of mechanical products. For example, the wear resistance and dimensional stability of machine tool castings directly affect the accuracy and maintenance life of machine tools; The size, accuracy and surface roughness of impellers, shells and internal cavities of hydraulic parts of various pumps directly affect the working efficiency, energy consumption and cavitation development of pumps and hydraulic systems; The strength and heat shock resistance of castings such as cylinder block, cylinder head, cylinder liner, piston ring and exhaust pipe of internal combustion engine directly affect the working life of the engine.

Consumers are the supporters of the market, and their demand capacity has become the production standard of enterprises. Enterprises should determine the production capacity according to the market. Therefore, the market research of enterprises is particularly important. It is a bridge to connect consumers and a paving stone for product sales.

The market investigation of casting products can enable casting enterprises to fully understand the situation of casting consumption market before arranging production. Such as casting demand, demand type, demand manufacturer, product requirements and other information. In a large amount of information, casting manufacturers can choose their own fields with wide consumer market for production; If there is no suitable one, the enterprise also has enough time to adjust production and produce casting products required by the market, so as to effectively prevent overcapacity of castings.

There are many factors that affect the quality of castings, and the design process of castings. During the design, in addition to determining the geometry and size of the casting according to the working conditions and the properties of metal materials, the rationality of the design must also be considered from the perspective of casting alloy and casting process characteristics, that is, obvious size effect, solidification, shrinkage, stress and other problems, so as to avoid or reduce the occurrence of defects such as component segregation, deformation and cracking of the casting.

There should be a reasonable casting process. That is, according to the structure, weight and size of the casting, the characteristics of the casting alloy and the production conditions, the appropriate parting surface, molding and core making method are selected, and the casting ribs, cold iron, riser and gating system are reasonably set. So as to ensure high quality castings. The third is the quality of raw materials for casting. The substandard quality of metal furnace charge, refractory, fuel, flux, modifier, casting sand, molding sand binder, coating and other materials will cause defects such as porosity, pinhole, slag inclusion and sand sticking in the casting, which will affect the appearance and internal quality of the casting. In serious cases, the casting will be scrapped. The fourth is process operation. It is necessary to formulate reasonable process operation procedures, improve the technical level of workers, and ensure the correct implementation of the process procedures.